The good point over the SimpleFactory is you can subclass it to implement different ways to create objects
For simple case, this abstract class could be just an interface
This pattern is a "real" Design Pattern because it achieves the "Dependency Inversion Principle" a.k.a the "D" in S.O.L.I.D principles.
It means the FactoryMethod class depends on abstractions, not concrete classes. This is the real trick compared to SimpleFactory or StaticFactory.
You can also find these code on GitHub
FactoryMethod.php
.. literalinclude:: FactoryMethod.php :language: php :linenos:
ItalianFactory.php
.. literalinclude:: ItalianFactory.php :language: php :linenos:
GermanFactory.php
.. literalinclude:: GermanFactory.php :language: php :linenos:
VehicleInterface.php
.. literalinclude:: VehicleInterface.php :language: php :linenos:
Porsche.php
.. literalinclude:: Porsche.php :language: php :linenos:
Bicycle.php
.. literalinclude:: Bicycle.php :language: php :linenos:
Ferrari.php
.. literalinclude:: Ferrari.php :language: php :linenos:
Tests/FactoryMethodTest.php
.. literalinclude:: Tests/FactoryMethodTest.php :language: php :linenos: